Doug McMillon, a Long-Serving Insider, Will Be Youngest CEO Since Founder

Wal-Mart Stores Inc. named Douglas McMillon as its next chief executive, handing the job to a long-serving insider who, at just 47 years old, will be the youngest CEO since Sam Walton to helm the giant retailer.

In a sense, he represents a generational shift at the company as its traditional model of big U.S. stores comes under pressure from smaller retailers and a shift to the Web. Yet Mr. McMillon is a tried-and-true company man...